Andiamo a vedere la Stella Marina del Grignone

La stella marina del Grignone
La stella marina del Grignone

Leggi anche: La Stella Marina del Grignone …sempre su scienzafacile.it

A Barzio è cominciata la Sagra delle Sagre e sarà di nuovo possibile andare ad osservare i vertebrati fossili delle Grigne e alcuni calchi di fossili trovati durante gli scavi dell’università di Milano.
L’estate della Valsassina e del Lecchese propone anche alcune interessanti serate scientifico-divulgative ed un’escursione tenute dal Professor Andrea Tintori, Paleontologo del dipartimento di Scienze della Terra dell’Università degli Studi di Milano. (dettagli in fondo all’articolo)
Lo scavo, la preparazione, lo studio di questi fossili e la realizzazione dei calchi ha richiesto diversi anni di lavoro sia sul campo, sia in laboratorio e molto sarà ancora da fare.
Eccomi quindi di ritorno in Università per realizzare alcuni nuovi calchi di fossili.
In realtà, ho solo dovuto pitturarli per renderli simili agli originali. La tecnologia utilizzata per questi calchi è infatti quella della scansione e della stampa 3D.
In Italia è diventato illegale realizzare le matrici (ovvero gli stampi) dei fossili in silicone per la colata successiva di resina o gesso.
Non ho molta esperienza di scansione e stampa 3D.
Da quello che ho visto fino ad ora però la qualità dei calchi che mi sono arrivati è piuttosto scarsa e il costo decisamente elevato.
Ho analizzato nel dettaglio l’originale della stella marina del Grignone e il suo calco, più che una copia di un fossile, sembra un quadro impressionista.

originale vs calco prima della colorazione
originale vs calco prima della colorazione

Da un metro di distanza sembra uguale all’originale, anche perchè come sempre l’ho dipinta con molta cura dei dettagli, ma da 50 cm sembra una carta geografica con le isoipse (le curve di livello) all’incirca ogni 0.1mm che danno solo l’idea di un rilievo a forma di stella (si vedono molto bene le caratteristiche della stampa in alto a sinistra nella foto di apertura).
Le spine e i limiti tra le varie piastre dello scheletro non si vedono minimamente…
Questo è un dettaglio insufficiente e inutilizzabile per qualsiasi fine di studio o esposizione di una certa qualità.
Anche pitturare la roccia è stato molto difficile perchè non ne viene riproposta la granulosiutà e non si possono dipingere i rilievi con la tecnica del pennello asciutto che ho sempre utilizzato per pitturare i calchi.
Non parliamo di quanto sarebbe inutile fare calchi di pesci con ornamentazione sulle ossa e sulle scaglie, finissimi raggi di pinne, ecc.

calchi di pesci fossili
calchi di pesci fossili

Scienzafacile è un sito propositivo, non disfattista, quindi ecco la mia proposta per risolvere la questione.
Non può essere la Sopraintendenza ai beni Archeologici ad occuparsi di paleontologia e a dettare le leggi a riguardo.
Per quanto mi riguarda sono i PALEONTOLOGI che dovrebbero dettare le leggi riguardanti i fossili e la Sopraintendenza dovrebbe solamente farle rispettare.

Ctenognatychthis
Ctenognatychthis

Comunque sia, i fossili del Grignone vi aspettano.
Non sono stati cercati per poi essere messi in cantina. Al contrario i lavori e lo studio su questi esseri viventi del passato sono  attivi ed è possibile seguire il tutto pubblicamente, ai piedi delle montagne da cui provengono i reperti.
Buone vacanze da scienzafacile.it

…e fatevi un bel giro in Valsassina!

Ste e la stella colorata!!!
Ste e la stella colorata!!!

Il programma delle serate:

Lunedì 12 Agosto h 20:30 a Esino Lario, edificio Asilo.

Mercoledì 14  Agosto h 20:30 a Barzio, sala civica.

http://www.valsassinanews.com/index.php?page=articolo&id=13910

Escursione guidata agli Scudi del Grignone:

Ritrovo sabato 17 agosto h 9:00 al laghetto dell’Alpe Coa.

Prenotazione obbligatoria per salita in Auto e assicurazione, presso la sede della Comunità montana “Valsassina, Valvarrone Val d’Esino e Rivera”.

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